Notes, summaries, assignments, exams, and problems for Biology

The Cell Cycle

The cell cycle consists of two main phases: interphase and mitosis (M phase) [3].

Interphase

Interphase is further divided into three phases:

1. G1 phase (Gap 1): During this phase, the cell grows in size and carries out normal metabolic activities [4].
2. S phase (Synthesis): In this phase, DNA replication and chromosome duplication occur [4].
3. G2 phase (Gap 2): The cell continues to grow and prepares for cell division [4].

Mitosis (M phase)

Mitosis is the actual phase of cell division and is divided into four stages:

1. Prophase: Chromosomes condense, the nuclear envelope and nucleolus disappear, and spindle fibers start to appear [4].
2. Metaphase: Chromosomes align at the equatorial plate [4].
3. Anaphase: Centromeres divide, and chromatids move towards

Basic Concepts

Characteristics of Living Things

• Movement - motion where the organism will go from one place to the other
• Responsiveness - how any organism reacts
• Growth - an organism's ability to get bigger
• Reproduction - ability of an organism to produce offspring
• Respiration - the ability of an organism to gain oxygen from food
• Digestion - ability of an organism to break down food
• Absorption - ability of an organism to take in nutrients
• Circulation - ability of materials to go through the body
• Assimilation - food is taken in and changed to something essential
• Excretion - ability of our bodies to remove waste

Homeostasis and Regulation

How does Fixism explain the diversity of living things?

(4 marks) Fixism claims that species were created the way they are now, given that they do not change. Therefore, the diversity we find today is the diversity that has always existed. c.

Explain why two very different species such as birds and butterflies can have similar wings, responsible for the same function. Which evidence of evolution is it? (4 marks)

Given that both species must adapt to the same environment, they end up developing similar structures. It is an example of convergent evolution.

According to Darwin, why do individuals compete against each other? What are the consequences of this constant competition? (4 marks)

The cause is the lack of resources in an environment and the... Continue reading "Explaining Diversity of Living Things: Fixism, Evolution, and Ecological Factors" »

Eyes

Orbital Hematoma (Black Eye)

An orbital hematoma, commonly known as a black eye, results from a blow to the area surrounding the eye, which causes capillary bleeding.

Signs & Symptoms:

• Noticeable swelling and discoloration around the orbit.

Orbital Fracture

An orbital fracture is caused by a direct blow to the eyeball, forcing it posteriorly. This action compresses the orbital fat until a blowout rupture occurs to the floor of the orbit.

Signs & Symptoms:

• Diplopia (double vision)
• Restricted eye movement
• Downward displacement of the eye

Hyphema

A hyphema is a collection of blood in the anterior chamber of the eye, typically resulting from blunt trauma to the eye. This is a major eye injury that can lead to serious problems.

Signs & Symptoms:

The Nervous System

Cranial Nerves

Twelve pairs of cranial nerves enter and exit the brain, comprising sensory, motor, and mixed types. They innervate the head, upper torso, and some internal organs. Some cranial nerves are associated with the autonomic nervous system. Along their pathways, ganglia—groups of neuronal cell bodies—can be observed.

Spinal Nerves

Thirty-one pairs of mixed spinal nerves emerge from the spinal cord. Each nerve originates as two distinct roots—dorsal and ventral—which merge to form a single nerve cord. Sensory neurons enter the spinal cord through the dorsal root, while motor neurons exit through the ventral root.

The Autonomic Nervous System

The autonomic nervous system (ANS) regulates involuntary bodily functions.... Continue reading "The Nervous and Endocrine Systems: A Comprehensive Overview" »

Special diets:

-Low cholesterol diet

-Low salt diet

-Gluten free diet

-Diabetes diet

-High or low calorie diets

Excretion:Is the process of

eliminating or expelling waste

matter from our bodys.

Excretion of CO2: Carbon

dioxide is produced during

cellular respiration and is

excreted from the body by

the lungs.

Wastes that are solids:The urine

and the sweat.

The urine:This is usually yellow

or transparent , but it can be

opaque when there is a lot of

waste. More or less the 95% is

water and the other 5% are

dissolved substances .The

composition is similar to blood

plasma .Urea is the primary

waste molecule in the urine .

Sweat:Is similar to urine but is

more dilute , approximately 99%

water.

sweat glands.The tiny , tubular

structures within the skin expel

Human Beings and Health

The World Health Organisation (WHO) defines health as 'the complete physical, mental and social well-being, not only the absence of disease'.

Factors that Influence Health

The environment: healthy surroundings should be free of biological, physical or chemical elements that are harmful to your health.
Personal characteristics: genetic factors, age and gender predispose people to suffer from certain types of illnesses.
Lifestyle: healthy habits and lifestyles are very important for staying healthy.
Healthcare: it is essential to have an efficient healthcare system to guarantee public health.

Vital Signs

Vital signs are physiological parameters that inform us of our state of health or the evolution of a disease.